Re: [Brahms-l] Npart and Ncoll calculator - now with errors...

Hi Pawel,     The uncertainty that you quote corresponds to a 5%  
multiplicity uncertainty.  It is
NOT the systematic uncertainty on Ncoll.   For the systematic  
uncertainty you need to consider
the Glauber model calculation uncertainties.   If you go to the  
bottom of the table you will
see these quoted at the +uncertainty and -uncertainty.
Regards,
Steve

On Jul 20, 2006, at 5:55 AM, Pawel Staszel wrote:

> Dear Steve,
> I'm trying to plot the systematic error band on the plot showing  
> forward Raa versus N_part (AuAu_at_200 run04).
>
> What I need is an error on Ncoll. In the Radeks macro I see   886.8 
> +-39.3 for centrality 0-10%  and
> 534.3+- 45.8 for centrality 10-20%. Now, using your calculator for  
> the same centrality classes I got
> the same n_coll but quite different errors, namely 10.1 for 0-10%  
> and 21.3 for 10-20%. Probably Radek was using
> previous version of the calculator.
> Could you comment on this?
> Thanks,
> Pawel.
>
> Stephen Sanders wrote:
>
>> Hi,   I have updated the Npart and Ncoll calculator at
>> http://kunuc10.phsx.ku.edu/~sanders/cent2npart.html
>> to include the calculations needed to deduce Glauber model
>> uncertainties.  At the moment the calculations are done for 62.4  
>> and  200 GeV AuAu.
>> The new results are reasonable consistent with the latest draft  
>> of  the 62.4 GeV paper,
>> although the quoted 0-10% Ncoll uncertainty may be a little low.
>>
>> I tried to include enough detail on the page to make clear what  
>> was  done.  If not, let
>> me know and I'll try to clarify.   Each of the RHIC experiments  
>> seems  to be making its own
>> assumptions as to the Glauber model parameters and their   
>> uncertainties.  I've taken something of
>> a composite approach.  Several references are given with the   
>> calculation results.
>>
>> Following up on a question JH posed at last Thursday's meeting,  
>> the  calculator also includes a Ncoll(central)/Ncoll(peripheral)   
>> option.     This allows us to explore the
>> uncertainties on this ratio.   Unfortunately, the uncertainty on  
>> the  total multiplicity yield is one of the
>> larger error terms.  This term does not tend to cancel out in  
>> taking  the ratio.
>>
>> Comments, suggestions and questions are welcomed...
>>
>> ...steve
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>>
>
> -- 
> ----------------------------------------------------------------------
> | Pawel  
> Staszel                                                        |
> | Jagiellonian  
> University                                              |
> | Institute of Physics            email:       
> ufstasze_at_if.uj.edu.pl    |
> | Reymonta 4                      phone:      (+48) 12 663  
> 5705        |
> | Krakow 30059                    FAX:        (+48) 12 633  
> 7086        |
> |  
> Poland                                                               |
> ----------------------------------------------------------------------
>
>
>

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